1. Field of the Invention
Fluid storage tanks are used in a variety of areas. Common are those seen on trucks transporting a variety of fluids such as liquid nitrogen, milk, water, and other liquids. The most common type of truck is a trailer rig which is towed by a tractor rig. Other common types include fluid storage tanks mounted on a truck chassis similar to a 4xc3x974 or 6xc3x976. These type of vehicles are common to carrying fuel oil or diesel to fill homes with heating oil or tanks for generators. Construction sites use fluid storage tanks mounted on trucks to wet down the dry earth in order to prevent dust from intruding on nearby neighborhoods.
Most tanks have an elliptical cross-section and extend for some length, which provides the volume desired by the user. Other tanks have rectangular or square cross sections with rounded corners. Many of the previously described shaped tanks have a lower portion that extends downwards, and provides the ability to gravity drain the fluid to a central point on the tanker without the use of accessory pumps to drain the liquids from the tanker.
In order to prevent catastrophic failures of the tanks, internal baffles are installed into the tankers to reduce the pressure head of the fluid in motion, which in turn will reduce the amount of force on the front or rear caps, preventing the fluid from bursting through the fluid storage tank.
When the tankers are taken over very rough roads, there is substantial danger that the trailers or the truck may overturn because of its high center of gravity since the center of gravity is generally along the geometric center of the cross section, which is mounted high over the chassis of the truck.
2. Description of the Prior Art
Fluid storage tanks are known in the prior art.
U.S. Pat. No. 4,136,973 by van der Lely discloses a MOBILE DEVICE FOR TRANSPORTING LIQUID SUBSTANCES. The patent describes a cylindrical tank that has guide members disposed inside, where the guide members are positioned in such a was as to promote mixing of the liquid and solid matter enclosed therein when the vehicle stops its forward motion. The inertia of the material inside the tank causes a surge that forces the liquid over the inclined guide member and promotes mixing. The additional motions of the vehicle causes swirling and recirculating motions to further mix the solid and semi-solid matter. The patent is primarily describing a tank for transporting a mixture of manure and a further liquid, usually water.
U.S. Pat. No. 4,611,724 by Watkins et al., discloses a FLUID-STORAGE TANK. This patent discloses a tank for storing fluids. This tank is disclosed having a generally rectangular cross section with a number of reinforced internal baffles. The internal baffles are positioned so that access to each bay is on alternating sides. While the patent initially discloses an elongated shell, the primary disclosure of the patent is the geometry of the baffle(s) used to support the shell of the tank. The baffle disclosed is geometrically defined as a convexo-concave shell having 2 points of inflection where the concave portion has at least 1 horizontal planar rib to support and stabilize the baffle(s). The baffle(s) have 2 convex shapes and one concave shape joined together as one piece.
U.S. Pat. No. 5,630,625 by Shaw discloses a TANK TRUCK. This patent discloses a fuel delivery truck that has a pair of tag wheels that lift up when the amount of liquid in the tanks is reduced to a minimum point. This allows the tanker to turn with a smaller radius than it would with an additional pair of wheels on the ground at the rear of the vehicle. An additional disclosure is to position the hose assembly at the front of the tank, with a corresponding overhang, which maintains the overhang of the rear mounted hoses.
The purpose of the present invention is to provide a fluid storage tank that maximizes the volume of the fluid carried while substantially lowering the center of gravity of the tank.
It is a further object of the present invention to provide improved visibility for the driver by moving the mirrors closer to the cab, since the trapezoidal shape is smaller at the top of the tank than at the bottom.
The object of this invention will be achieved by providing an elongated shell, where the shell is in the shape of a trapezoid. The top of the trapezoid is smaller than the bottom of the trapezoid, which will noticeably lower the center of gravity of the tanker truck or trailer. The trapezoidal tank has an upper and a lower portion and is permanently attached to the side portions. The side portions may be identical, which will reduce overall tooling and part costs. The lower portion of the tank may have an additional reservoir, or sump. The reservoir or sump would fit between the rails of the truck or trailer chassis and further lower the center of gravity. Baffles would be attached to the external shell supporting the structure, and they would provide needed protection from the fluid building a large pressure head when the vehicle is stopped or started.